Piston-packing.



Patented Aug. 7, I900.

M. F. COX.

- PISTON PACKING. (Application filed Sept 23, 1899.)

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M. F. COX. PISTON PACKING.

(Application filed Sept. 23, 1899.)

Patented Aug 7, I900.

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IITED STATES PATENT FFICE.

PISTON-PACKING.

$IPECIFICATION forming part of I Letters Patent No. 655,202, dated August '7, 1900.

' Appliwtion filed September 23 1899. Serial No. 731,445. (No model.)

To all whom it may concern.-

Be it known that I, MILLARD F. COX, a citizen of the United States of America, and a resi= dent of Richmond, in the State of Virginia, have invented certain new and useful Improvements in Piston-Packings, of which the following is a specification.

My invention relates to piston-packings, and especially to that class in which the packing is effected by means of cut or split rings fitted into circumferential grooves in the periphery of the piston. This form of packing has some disadvantages, particularly in the case of large pistons. These disadvantages, which unless provided against are a source of considerable trouble, arise from two causes. The packing-ring must of necessity be cut at some point in order to allow it to expand and contract to adjust itself to the walls of the cylinder. This cutting of the ring forms a passage which unless covered will allow the steam to pass from one sideof the piston to the other, thereby causing a waste of steam. It also presents the cut ends of the ring to the action, of the steam, which acting as a wedge forces the ends of the ring apart and cause it to bear with too great a pressure on the walls of the cylinder, materially hastening the wear of the latter. This is proved'by the fact that the wear is greater at the ends of the cylinder than it is at the center, and this is due to the steam-pressure in the cylinder being greatest at the commencement of the stroke.

The object of my invention is to overcome these disadvantages, and it does so by preventing the admission of the steam between the ends of the rings.

In the drawings which accompany and form a part of this specification, and in which like numerals indicate like parts, Figure I is the plan of a piston fitted with my device. Fig. II is a section on line a b in Fig. I. Fig. III is a section of a part of the piston, drawn on a larger scale, on line 0' d in Fig. II. Fig. IV is a broken view in section of a part of the piston, showing my device. Fig. V is similar to Fig. IV, but shows'a slight modification. Fig. VI is a broken view in elevation taken from Fig. IV; Fig. VII is a broken view in elevation taken from Fig. V. Fig. VIII is a detail in perspective showing the plug.

In Fig. I, 1 is the piston, having in its periph ery the grooves 2, in which are fitted the packing-rings 3. In a socket 4 in the periphery of the piston and in line with the grooves I fit a plug 5, which has cut in it the two slots 6 6, forming the side walls 7 7 and the central wall or rib 8. The slots 6 6 are so cut that the inner faces of the side walls shall when the plug is in position be in alinement with the sides of the groove. This can be clearly seen in Fig. IV. The two ends of the ring have cut in them slots 9 9, which neatly en gage the centralrib 8, the said slots being sufficiently deep to allow for the expansion and contraction and a small endwi'se movement of the ring. The two prongs or tongues thus formed in the ends of the rings neatly fit in the two slots 6 6 in the plug 5. On the bottom of the plug is a projectionlO, which fits in the extension 11 of the socket. Now this projection 10 and the extension 11 of the socket are not absolutely necessary to the working of the plug, but they have their ad vantages. In'the first place the'preliminary drilling of a hole, such as one of the diameter of the extension 11, through themetal renders the subsequent accurate drilling and reaming of the socket 4: much easier and cheaper than they would be were the preliminary hole not drilled. It should be noted here that the drilling of the preliminary hole need not be continued completely through the metal. In the second place the projection 10 forms a handy means for securing the plug in the lathe-chuck for turning, and fitting neatly in the :extension 11 it helps to give the plug 5 a good bearing.

Referring to Fig. IV, it will be seen that the two side walls 7 7 of the plug 5 will prevent the passage of steam between the ends of the ring. It will also be seen that the walls 7 7 and the central rib 8 will prevent the passage of steam from one side of the piston to the other and also that the central rib 8 will prevent the ring from slipping around in its for it as follows: In vertical engines, and'in certain cases in horizontal engines, I prefer to attach one end of the packing-ring to the plug by means of a pin 12, as shown in Figs. I. II. III. IV. and- VI. The plug having a neat sliding fit in the socket will then vwork with the ring, always makinga flush surface with the latter; but in some instances, particularly so in the case of large horizontal engines,'I find it, by placing my plug or plugs, if A there be more than one packing-ring at the bottom of the piston, as shown in Figs. I and II, unnecessary to pin'the end of the ring to the plug. The piston is usually turned slightly smaller than the bore of the cylinder, and the packing-ring will therefore project slightly beyond the face of the periphery of the piston, I therefore set my plug, which fits not too tightly in its socket, so that it projects from the face of the periphery of the piston just as much as the packing-ring does. (See Fig. V.) The socket being of just the same depth as the plug, there will now be a space between the bottom of the plug and the bottom of the socket equal to the amount that the plug projects beyond the piston. Now after the engine has been at work fora little while and after the different stuffing -box packings, 850., have worna little the piston will 'bottom";-that is to say, the piston will ride upon the bottom of the cylinder. If the plug 5 were so tight in the socket at that it could not vmove, or, being movable, if its length were even slightly in excess of the depth of the socket, it would prevent the piston from bottoming, and the weight of the piston would therefore be carried by the plug, which, bearing on the Wall of the cylinder, would soon cut a groove in the latter. It is true that the plug might bemade of a softer material than thatof which the cylinder-walls are constructed; but this would be almost as bad as the evil it was sought to avoid, for the edges of the walls and rib of the plug would of the rings in the grooves 6 6; but since the plug 5 is made movable in the socket 4 it will, when the piston tends to bottom, take up with the rings, its outer faces always presenting'a flush surface with the outer face of the ring. A When the piston has fallen so much that it actually rides on the cylinder-wall, the outer face of the plug and rings will then form one surface with the bottom of the peripher'y of the piston, all three then bearing "on the cylinder-wall.

Having now described my invention,what I claim, and desire to protect by United States Bettor's Patent, is-

1. The combination of a piston having a circumferential groove, a movable cylindrical plug slotted so asyto format its outer end two side walls and a central rib, thesaid plug be= ing adapted to be inserted in a socket in the piston so that whenthe plug is in place the inner faces of its'side walls shall be in alinement with the Walls of the circumferential groove in the piston, and a packing-ring occupying the said circumferential groove and having slotted ends adapted to engage the central wall in the plug, and having one of its ends securedto the plug.

circumferential groove, a movable cylindrical plug slotted so as to form at its outer end two side walls and a central rib, the said plug being adapted to be inserted in a socket in the piston so that when the plug is in place the inner faces of its side walls shall be in alinement with the walls of the circumferential groove in the piston, and a packing-ring occupying the said circumferential groove and having slotted ends adapted to engage the central wall in the plug.

Signed by me at Richmond city, Virginia, this 7th day of September, 1899. H

MILLARD F. COX.

Witnesses:

ARTHUR SORIVENER,

soon turn with wear and would jam the ends EUGENE J ONES.

2. The combination of a piston having a v 

